Cell surface membrane glycoprotein structures and functions have been studied using the methods of surface labeling with I-125 of H-3 followed by two-dimensional isoelectric focusing and SDS polyacrylamide gel electrophoresis and autoradiography or fluorography. Membrane protein change during the chemical induced granulocyte differentiation of human promyelocytic leukemia HL-60 cells include the appearance of a major surface protein which is also found in normal human granulocytes and was identified as a terminal myeloid differentiation related marker. A similar analysis of a number of cytodifferentiation-inducer resistant HL-60 sublines revealed surface protein patterns in dimethylsulfoxide and 5-bromo-2'deoxyuridine inducer resistant sublines which are very similar to wild type HL-60. In contrast, retinoic acid and 6-thioguanine resistant sublines exhibited drastic differences from wild type cells. Regardless of surface pattern, upon induction of differentiation, all cell lines revealed the same newly synthesized terminal myeloid differentiation surface protein.